21744290 has 16 divisors (see below), whose sum is σ = 39529080. Its totient is φ = 8611200.

The previous prime is 21744277. The next prime is 21744293. The reversal of 21744290 is 9244712.

It can be written as a sum of positive squares in 4 ways, for example, as 19123129 + 2621161 = 4373^2 + 1619^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21744293) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9755 + ... + 11774.

Almost surely, 2^21744290 is an apocalyptic number.

21744290 is a deficient number, since it is larger than the sum of its proper divisors (17784790).

21744290 is a wasteful number, since it uses less digits than its factorization.

21744290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21637.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21744290 is about 4663.0773101033. The cubic root of 21744290 is about 279.1140791517.

The spelling of 21744290 in words is "twenty-one million, seven hundred forty-four thousand, two hundred ninety".